Duplex telegraph.



No. 887,038. PATENTED MAY 5 1908.

' J. J. GHEGAN.

DUPLEX TELEGRAPH. 7 APPLICATION FILED MAY 20, 1907.

N INVENTOE rromvsy's JOHN J. GHEGAN, F NEWARK, NEW JERSEY.

DUPLEX TELE GRAPH.

Specification of Letters Patent.

Patented May 5, .1908.

Application filed May 20,1907" Serial No. 374,606.

To all whom it may concern: Be it known that I, JOHN J. GHEGAN, a citizen of the United States of America, re-

sidingin the city of Newark, county of Essex, State of New Jersey, have invented cer' tain new and useful Improvements in Duplex Telegraphs, ofwhich the following isa specification.

The object of my invention is to provide a simplified system of duplex telegraph, which while applicable in connection with various forms of relays, including difierential or double wound relays, is especially useful in its applicability to the ordinary single wound instruments and line current arrangements without requiring any change in them.

By the use of my invention it is possible to have one or more intermediate stations in the into effect.

circuit, and to duplex an ordinary way cir- 1cuit for all or only some of the offices, on the A characteristic feature of my invention consists in providing in connection with the relay and ordinary equipment in each office a transmitter and two artificial resistances, one of which is in a shunt around the relay and is thrown into circuit on the closure of the local transmitter circuit at the same instant that the other resistance (which is in circuit in the main line when transmitter is open) is shunted or short-circuited;so that by thus decreasing or increasing the resistance of the line circuit, all relays except that at the transmitting station will'respond.

. The diagram in the accompanying drawing illustrates a convenient form or arrangement by which my invention may be carried In this diagram I have shown three stations, marked 1, 2 and 3, the ar rangements for the several stations, whether terminal or intermediate, being alike.

At terminal station 1, I have indicated a ground connection at E and a generator at G, and'at the other terminal station I have indicated a ground connection at E and. a generator at G Theline connection from the generator G passes through the coils of the ordinary single wound Morse relay R and thence through conductors 5, 6 and through.

artificial resistance Rh to the line leading to the next station. 'At F is a branch'or shunt 7. containing an artificial resistance AR and connected to the armature 8 of a pair of'ele'ctromagnets e, e in the local transmitter circuit T, containing-a local battery b and transmitter key k'. The other armature 8 of the '710 and, 11*10 are open).

station 3 Wishes -to transmit to station 1,

transmitter 'electromagnets is connected through wire 10 to the line leading to the next station (or in the case of station 3 .to the generator G The front stops 9, 9 of this double contact transmitter are electrically connected witheach other so that when the local transmitter circuit is closed, the shunt circuit around the relay R is closed through 7, resistance AR, armatures 8, 8 and wire 10. The wire 5 is also connected through wire 11 to the front stop 9 I prefer to make both resistances AR and Rh adjustable, al-

though the result may be accomplished by the adjustment of the resistance AR only. To simplify the diagram, the local circuits of the relays R have not been shown.

In the diagram I have indicated the transwhile open at station 1.

When the transmitter circuit is open, as shown at 1, the current has only one path to follow; that is through the relay R and resistance Rh,'but when the transmitter circuit is closed, the current can then flow through the shunt 7, 8, Q, 8 10 containing resistance AR, as well as through the relay R, wire 11, armature 8 and wire 10, in shunt around resistance Rh. I The transmitter circuits are normally closed, and the relays R are so adjusted that when these shunt circuits at the different stations are closed accordingly, and all the resistances Rh are thus cut out,,.the armatures of the relays R will be drawn up to their front sto s. But when a transmitter key is is opene at the transmitting station, and the two shunt circuits 710 and 1110 around the relay and its resistance Rh are thereby broken or opened, as shown at station 1, the line resistance is increased by the conse uent introduction of theresistanc'e Rh, at t e transmittin sta-- tion, so as to cause the arinatures of t e relays R at the other stations to be released, to

mitter circuits are closed at stations 2 and 3 their back stops, as indicated at stations 2 and 3.

The armature of the relay R at the transmitting station is not released, however, be-

cause the resistance in the shunt 710 is so proportioned to that of the relay R as to give approximately the same magnetic pull to the relay when it is getting a portion of the stronger current (on-closure of the shunts) as it has when the entire weaker current is passing through the relay coils (when the shunts Therefore if of the offices on the line may be duplexed,

that the (luplexed offices can work with nonduplexed ones by having an ordinary key in the line circuit, and that by substituting another transmitter for the ordinarysounder,

lines duplexed in this manner can automatically repeat to each other.

I claim as my invention:

1. A duplex telegraph system, having arelay and adjustable resistance inthe line in combination. with two shunt circuits, one around the relay and the other around said line resistance, anda transmitter controlling said shunt circuits, whereby the operation of the transmitter increases or decreases the resistance in the line to operate a distant relay without afieeting the relay at the transmitting'station.

2. A duplex telegraph system, having a relay and adjustable resistance in the line in combination with twoshunt circuits, one around the relay and the other around sald line resistance, and a double contact transmitter controlling said shunt circuits, where'- by the operation of the transmitter increases or decreases the resistance in the line to operate a distant relay withoutiaffecting the relay at the transmitting station;

3. A duplex telegraph system, having a relay in circuit with a resistance, ashunt .cir-

cuit through the relay but around sai'dfrsistance, and another shunt circuit around the relay and containing a resistance in comb1nat10n with-a transmitter to open and close said two shunt circuits.

with front stops connected in said two shunt circuits to open and close these shunt circuits.

In testimony whereof I have signed-my name to this specification, in the presence of two subscribing witnesses. JOHN J. GHEGAN. Witnesses:

WALTER R. BEACH, HUBERT HowsoN. 

